Stay bolt



v Nov. 18, 1941. w. r. KILBoRN ETAL STAY BOLT Filed July 20, 1939 INVENTOR William T..Kilb Urn' Gro 6 verl?. Greenslade M, MJQMQ 2 Patented Nov. 18, 1941 STAY BOLT William T. Kilburn, Pittsburgh, and Grover R. Greenslade, Scott Township, Allegheny County, Pa., assig-nors to Flannery Bolt Company, Bridgeville, Pa., a corporation of Delaware Application July 20, 1939, Serial No. 285,518

3 Claims. .(l. 85-1.5)

This invention pertains to boiler staybolts of the type having a tell-tale hole disposed longitudinally ytherein and is for a bolt of this character wherein provision is made for protecting the interior of the hole from corrosive influences.

As is well known in the art, it is the practice to provide staybolts used in boilers, particularly locomotive boilers, with `a longitudinally disposed passageway called a tell-tale hole that extends from the nre-box end of the bolt throughout the greater portion of the length of the bolit. The function of this hole is to indicate a fracture or defect in the bolt when the boiler is subjected to periodic hydrostatic tests, the hole allowing Water to leak or seep out of the re-box end of the bolt if the bolt is fractured to a point where the fracture or defect in the bolt opens up to allow water to enter the tell-tale hole when the boilerv is under hydrostatic pressure. The interior of these holes has to be kept free of foreign material because the lodgment of foreign material in the hole tends to prevent the escape of water from the hole when :the boiler is being inspected. The regulations of the Interstate Commerce Commission require that the holes be tested tol ascertain if they are clean throughout their full length before the boiler is subjected to hydrostatic tests.

When the bolts are in use in'locomotives the fire-box end of the tell-tale hole is closed by a porous ceramic plug. This plug is intended to prevent the entrance of solid particles into the holes. These porous plugs, however, permit any steam that might enter or form in the tell-tale hole of a defective bolt during the operation of the boiler to escape into the fire-box. These plugs of course are removed when the boiler is inspected. In the operation of the boiler, .the bolts are subjected to Varying conditions of temperature so that the body of air or gas filling the hole expands or contracts. This is often referred to as breathing Notwithstanding the Very fine porosity of the porous plugs, this breathing may cause small droplets of contaminated water to be drawn into the tell-tale hole. Also, oxygen and oxidizing gases are drawn from the fire-box into the tell-tale holes, the circulation of gases of course being relatively small. The air and oxidizing gases attack the interior of the bolt, particularly if the bolt is not lined with a protecting coating or if the protecting coating has been damaged or impaired. The resulting oxide, either alone or in conjunction with the ash that inltrates through the porous plug, compacts in the hole tending to form a stoppage, this compacted mass sometimes being so hard that it has to be drilled out. Even the presence of a very small amount of a non-conducting oxide at the extreme inner end of ,the hole will prevent the electrical tester, such as that shown in prior Patent No. 1,567,728 of Grover R. Greenslade, from making a sufliciently good electrical contact with the inner end of the hole to show that the hole is open. This tendency toward oxidation and compacting of foreign material in lthe hole is especially aggravated in those bolts located in certain portions of the boiler where steam jets are used to blow out deposits of flue dust or powdered ash. W'hen these steam jets are turned on there is condensed water in the jet system which is blown against the fire-box ends of the staybolts in this portion of the boiler and the water in conjunction with the air and oxidizing gases accelerates the corrosion of the iron of which the staybolts are formed.

'I'he purpose of the present invention is to protect the interior of the tell-tale hole from attack by oxygen and oxidizing gases or other corrosive gases by placing in the tell-tale hole a charge of a reactive agent, as for example a reducing agent which at the operating temperature of the bolts will react more readily with such air or gases than the metal of which the bolt is formed. The metal will thus be protected inasmuch as the small amounts of oxygen or other gas which enters the tell-tale hole will be consumed in reacting with the reducing agent instead of attacking the bolt itself. sufiicient charge of reagent to last from one period of inspection to another because even under periods of continuous use, the rate at which the reducing agent is consumed is extremely slow and boilers, especially locomotive boilers equipped with tell-tale exible staybolts, have `to be tested at least once a year.

Our invention may be more fully described in connection with the accompanying drawing in which Figure 1 is a sectional View through a portion of a boiler showing the staybolts in place and showing one form of reagent in the tell-tale hole;

Figure 2 is a fragmentary View similar to Figure 1 showing a different reagent in the tell-tale hole; and

Figure 3 is a View similiar to Figure 2 showing still another form of reagent,

Referring first to Figure 1, 2 designates the fire sheet of the boiler and 3 is the outer sheet. 4 designates the usual form of :dexible hollow staybolt assembly in which the staybolt has a longitudinally extending tell-tale hole 5 therein. This hole 5 terminates at one end in the spherical The tell-tale hole will hold a be sticks of Willow charcoal placed in end-to-end relation as illustrated in Figure 1. Instead of 'Willow charcoal, amorphous carbon inv any suitable or convenient form may be used. During the operation of the b oiler the bolts may be subjected of a small order such as those used in the probe to a temperature around 400 F. or higher, and at this temperature carbon will react with the oxyacid in character which makes it less desirable from this standpoint than charcoal or carbon or the alkali metals. It has the advantage of oxidizing at relatively loW temperatures and not so violently as the alkali metals, and from this standpoint it is desirable.

The oxidizable metals are preferably mixed with inert'material such as Silocel or diatomaceous earthso that the mass as a Whole Will have a relatively higher resistance to electric currents tester so that if the bolt is tested While some of the reagent is still in the hole, the probe tester gen that permeates the porous plug, convert it to carbon monoxide or carbon dioxide, and thus ,prevent oxidation of the bolt itself. The oxidava particularly desirable material for the purpose.

Carbon'also has another advantage in that it is a relatively poor conductor of low voltage electric currents and therefore when the bolt is inspected by an electric probe tester of the type disclosed in Grover R. Greenslades patent above referred to, if the carbon has not been completely consumed, it Will prevent the probe tester from making electrical contact with the end of the hole and will not itself conduct sufflcient current to` show the hole to be open. It is therefore not possible for any false indication to be given as would be the case if the reagent were a' good conducting metal.

In Figurev 2 the bolt as shown in Figure 1 is illustrated and the same reference numerals have beenused to describe it. Instead of the reagent being illustrated as being in stick form, it is illustrated :as comprising granular particles. This granular material may be carbonaceous or it may be comprised of some readily oxidizable metal in finely divided form in which case it is preferably mixed with inertmaterial 'such' as diatornaceous earth or Silooel, or it may comprise a, mixture of carbonaceous particles and metallic particles. Examples of metals-as may be used are the alkali metals, sodium and'potassium, or some of the readily oxidizable earth metals as magnesium or in some cases aluminum, or it may be comprised of phosphorus, preferablyA red phosphorus. In Figure 2 the mass of reagent With or without inert material is designated 8.

Instead of the'material being loose as shown f in Figure 2, the material -similar to that used in Thevv oxide of phosphorus'is` will not give a clear-hole indication.

While we have illustrated one particular form of staybolt for the purpose of describing our invention and which is a common form now in general use,it Will be understood that the invention is applicable to all staybolts in which a telltale passage or opening is provided.

All of the various forms of our invention herein specifically described are intended to provide a chemical agent in the tell-tale hole Which Will combine with oxygen or other corrosive gases that may enter the tell-tale hole and thereby prevent such gases from attacking or corroding the Wall Aof the tell-tale hole. This not only affords a protection tothe bolt, but reduces the likelihood of `any compacted mass of foreign substance accumulatingin the hole to such extent that the hole has to lbe drilled out in order to be tested. While specific reagents have been illustrated and described, it Will be understood that thesea-re illustrative of our invention and that various other reagents or reducing material may be used in 4place of `those herein specifically mentioned.

We claimas our invention.:

1. A boiler staybol-t having a head end and a fire 'box end andv having a tell-tale hole extending longitudinally thereof, a removable porous closure for the hole at the re box end of the bolt through which gases and moisture may be taken into or expelled from the staybolt While'leaving the'assembly intact, and a reagent in the telltale holeprotecting the interior of the hole from oxidation and corrosive gases.

2. A'boiler staybolt having a head end and a fire lboxiend and having la. tell-tale hole extending longitudinallyy thereof, a removable porous closure vfor the hole at the re box end of the bolt through which gases and moisture may-be taken intocr expelled from the staybolt while leaving the assembly intact, and carbon in amorphous form in ,the tell-tale hole protecting the interior of the hole from oxidationv and corrosive gases.

3. A boiler staybolt assembly comprising a staybolty vhaving a headen-d and a fire box end, and having a tell-taley hole therein opening through the fire box Vend of the bolt, a reducing agent in the hole and means for closing said fire box end ofthe hole, andA Which has minute gas passages therethroughl to allow for the escape of gases or Water from the interior of the hole and through which gases and vapors in the fire box mayfenter the hole, said'- reducing agent being effective to reduce oxidation on the interior of the bolt at the temperature'of operation.

' WILLIAM T.'IULBORN.

GROVER R. GREENSLADE. 

